ComboBox.ValueMember and DisplayMember

本文关键字：DisplayMember and ValueMember ComboBox | 更新日期: 2023-09-27 18:26:25

如何设置这些值？我有一个DataTable，里面有我想在组合框中设置的所有数据，但我找不到如何设置。

我试过

ComboBox1.DataSource = dataTable;
ComboBox1.ValueMember = "id"; // --> once hes here, he just jumps out the method
ComboBox1.DisplayMember = "name";

没有编译错误，没有警告，什么都没有。。跳出来！

这是填写DataTable 的查询

"Select * from '"Table'""

我与调试器进行了检查，数据表已填充。列名为"id"answers"name"。组合框为空。我是第一次填充它！

ComboBox.ValueMember and DisplayMember

您不应该按的顺序设置列表框和/或组合框的datasource

ComboBox1.DataSource = dataTable;
ComboBox1.ValueMember = "id"; 
ComboBox1.DisplayMember = "name";

相反，这是正确的顺序：

ComboBox1.ValueMember = "id"; 
ComboBox1.DisplayMember = "name";
ComboBox1.DataSource = dataTable;

注意：设置datasource应为最后一行。

如果您先设置datasource，SelectedIndexChanged事件将触发，您可能会得到强制转换错误或其他异常。

使用键值对填充组合框

填充组合框的一种巧妙方法是将数据源设置为键值对列表。它也可能启发使用存储在某种列表中的数据：

//Some values to show in combobox
string[] ports= new string[3] {"COM1", "COM2", "COM3"};
//Set datasource to string array converted to list of keyvaluepairs
combobox.Datasource = ports.Select(p => new KeyValuePair<string, string>(p, p)).ToList();
//Configure the combo control
combobox.DisplayMember = "Key";
combobox.ValueMember = "Value";
combobox.SelectedValue = ports[0];

数据源也可以使用以下语法填充：

ports.Select(p => new { Key = p, Value = p }).ToList();

technicue可以扩展为多个列列表的更多属性名称。

已经是键值对的对象（如Dictionary项）可以直接使用

combobox.DataSource = new Dictionary<int, string>()
{
    {0, "COM1"},
    {1, "COM2"},
    {2, "COM3"},
}.ToList();
combobox.ValueMember = "Key";
combobox.DisplayMember = "Value";

元组可以像这样初始化和使用

var ports= new List<Tuple<int, string>>()
{
    Tuple.Create(0, "COM1"),
    Tuple.Create(1, "COM2"),
    Tuple.Create(2, "COM3")
};
combobox.DataSource = ports;
combobox.ValueMember = "Item1";
combobox.DisplayMember = "Item2";

  ComboBox1.DataSource= dt; //the data table which contains data
  ComboBox1.ValueMember = "id";   // column name which you want in SelectedValue
  ComboBox1.DisplayMember = "name"; // column name that you need to display as text

它们接受字符串。。。

ComboBox1.ValueMember = "id"; 
ComboBox1.DisplayMember = "name";

我也遇到了同样的麻烦。在我的例子中，SelectedIndexChanged事件会触发并跳出该方法。尝试不使用SelectedIndexChanged事件。或者类似的东西：

ComboBox1.SelectedIndexChanged -= new System.EventHandler(ComboBox1_SelectedIndexChanged); 
ComboBox1.DataSource = dataTable; 
ComboBox1.ValueMember = "id";  
ComboBox1.DisplayMember = "name";
ComboBox1.SelectedIndexChanged += new System.EventHandler(ComboBox1_SelectedIndexChanged);

它对我有效。=）

ComboBox1.ValueMember = dataTable.Columns["id"].ColumnsName;   // column name which the values are not visible 
ComboBox1.DisplayMember = dataTable.Columns ["name"].ColumnsName;
 /* 
       column name that you need to select item by proprity : 
ComboBox1.SelectedItem; 
Or   you can use easly this : 
ComboBox1.Text; 
*/
ComboBox1.DataSource= dataTable; //the data table which contains data 
// and this should be last :)

public class ComboDeger {
    private string yazi;
    private int deger;
    public ComboDeger(string stryazi, int strdeger) {
        this.yazi = stryazi;
        this.deger = strdeger;
    }
    public string yazisi {
        get {
            return yazi;
        }
    }
    public int degeri {
        get {
            return deger;
        }
    }
}
private void combobox_doldur() {
    ArrayList ComboDegerleri = new ArrayList();
    ComboDegerleri.Add(new ComboDeger("9 : NORMAL", 9));
    ComboDegerleri.Add(new ComboDeger("10 : ENGELLİ", 10));
    comboBox1.DataSource = ComboDegerleri;
    comboBox1.DisplayMember = "yazisi";
    comboBox1.ValueMember = "degeri";
}
private void Form3_Load(object sender, EventArgs e) {
    con.Open();
    combobox_doldur();
    // Populate the COMBOBOX using an array as DataSource.
}

您可以像这样指定

  ComboBox1.ValueMember = "id";  
  ComboBox1.DisplayMember = "name";

也许不是所描述的问题，但在我的情况下，类型名称显示在组合框中，而不是DisplayValue中，尽管一切似乎都连接正确。结果发现，类型的公共属性是在没有getter和setter的情况下定义的！：）

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